Search found 613 matches

by ramarren
Sat Mar 17, 2012 6:28 am
Forum: Common Lisp
Topic: load problem
Replies: 1
Views: 2261

Re: load problem

The proper way is to use a system definition facility like ASDF. Otherwise you have to use MERGE-PATHNAMES to create a full pathname to the file you want to load, either by using saved absolute path or *LOAD-PATHNAME* variable. But that might break if anything is file-compiled.
by ramarren
Fri Mar 16, 2012 2:53 am
Forum: Common Lisp
Topic: Need a *general purpose* way to APPLY macros and special ops
Replies: 9
Views: 9207

Re: Need a *general purpose* way to APPLY macros and special

special operators can be called at runtime Special operators are not really "called" in the same sense that functions are. Special operators define a syntax for a certain operation. To construct the operation at runtime you have to build a code tree and then compile or interpret it. Honestly, I am ...
by ramarren
Fri Mar 16, 2012 1:58 am
Forum: Common Lisp
Topic: Need a *general purpose* way to APPLY macros and special ops
Replies: 9
Views: 9207

Re: Need a *general purpose* way to APPLY macros and special

regardless, so what about special operators then? They don't have any runtime issues... They do, what makes special operators special is that they are treated specially by the compiler/interpreter. You would have to construct the expression tree and then EVAL it for that to work, except that EVAL e...
by ramarren
Fri Mar 16, 2012 12:44 am
Forum: Common Lisp
Topic: Need a *general purpose* way to APPLY macros and special ops
Replies: 9
Views: 9207

Re: Need a *general purpose* way to APPLY macros and special

Macros are expanded at macro expansion time and special operators have a special meaning to the compiler, so you cannot use them at runtime without invoking the compiler or at least the interpreter. While sort of possible the performance and complexity penalty would most likely make that useless.
by ramarren
Tue Mar 13, 2012 3:32 am
Forum: Common Lisp
Topic: Strange Behavior: functions not work for a list/cons
Replies: 4
Views: 4287

Re: Strange Behavior: functions not work for a list/cons

Preface: Here is what happens with LIST-LENGTH in Common Lisp: LIST-LENGTH is in fact a standard Common Lisp function and works on my SBCL. It is specified to signal an error if the list is not a proper list or circular list, which are both subsets of lists. The specification for LISTP specifically...
by ramarren
Sun Mar 04, 2012 2:08 pm
Forum: Common Lisp
Topic: Hi!two very quick noobish questions
Replies: 3
Views: 3696

Re: Hi!two very quick noobish questions

You might want to read a book like Gentle Introduction to Symbolic Computation for a more detailed explanation. what is the real difference beetween '(1 2) and '(1 . 2),and if my conclusion is correct,why would anyone want to use something like '(1 . 2)...is it something like a tuple? The difference...
by ramarren
Thu Mar 01, 2012 11:08 pm
Forum: Common Lisp
Topic: Create a method dynamically for an instance of a class
Replies: 4
Views: 4137

Re: Create a method dynamically for an instance of a class

You might be interested in a prototype based object language extension such as Sheeple . Generally, adding function/methods at runtime is not the right thing, since if you are writing code calling them then you can just define them in the source and make them available at compile time, and if you ar...
by ramarren
Fri Feb 24, 2012 12:20 am
Forum: Common Lisp
Topic: Optimizing speed and fixnum literal
Replies: 7
Views: 8024

Re: Optimizing speed and fixnum literal

Also see SBCLs modular arithmetic . The entry in the manual is I believe out of date, and the capabilities of the compiler in this case are actually greater than described. If you know that the result is going to be a positive fixnum then wrapping the whole computation with (logand most-positive-fix...
by ramarren
Tue Feb 21, 2012 10:03 am
Forum: Common Lisp
Topic: LIST vs TICK in a LET causing a global side-effect?!?
Replies: 6
Views: 4780

Re: LIST vs TICK in a LET causing a global side-effect?!?

That was the key. Thank you. I can't decide if this is to be avoided or exploited...(feature or bug). Certainly for what I was doing it was bad. The "in undefined way" is important. Since the standard specifies the undefinedness explicitly , the implementation is allowed, but not required, to make ...
by ramarren
Tue Feb 21, 2012 6:10 am
Forum: Common Lisp
Topic: Finding number of saddle points of a matrix
Replies: 6
Views: 5858

Re: Finding number of saddle points of a matrix

See this Stack Overflow question. The complexity cannot be lower than O(xy) because you have to touch every point of the matrix.